In the 3rd Generation Partnership Project (3GPP) Evolved Packet System (EPS), a diagram of network architecture of the EPS in a non-roaming scenario as shown in FIG. 1 is composed of an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), a Mobility Management Entity (MME), a Serving Gateway (S-GW), a Packet Data Network Gateway (P-GW or PDN GW), a Home Subscriber Server (HSS), a Policy and Charging Rules Function (PCRF) entity and other support nodes.
An Application Function (AF) entity provides access points of service applications, and it is required to perform dynamic policy control on network resources used by these service applications. When the parameter negotiation is performed in a service plane, an AF transfers relevant service information to the PCRF entity. If the service information is identical with a policy of a PCRF, the PCRF accepts the negotiation; otherwise, the PCRF rejects the negotiation and gives service parameters which can be accepted by the PCRF in feedback at the same time. Afterwards, the AF can return these parameters to a User Equipment (UE). Wherein, an interface between the AF and the PCRF is an interface Rx.
The Policy and Charging Rules Function (PCRF) entity is a core of Policy and Charging Control (PCC), and is responsible for making policy decisions and charging rules. The PCRF provides network control rules based on service data streams, and these network controls include detection on service data streams, gating control, Quality of Service (QoS) control, and charging rules based on data streams and so on. The PCRF sends the policies and charging rules made by the PCRF to a Policy and Control Enforcement Function entity (PCEF) to perform enforcement, and meanwhile, the PCRF also needs to guarantee that these rules are identical with subscription information of a user. A basis of the PCRF making the policies and charging rules includes: acquiring information related to the services from the AF; acquiring subscription information of policy and charging control of the user from a Subscription Profile Repository (SPR); and acquiring information of networks related to bearer from the PCEF.
The Policy and Control Enforcement Function (PCEF) entity is generally located in a Gate-Way (GW), and executes the policies and charging rules made by the PCRF in a bearer plane. The PCEF detects the service data streams according to a service data stream filter in the rules sent by the PCRF, thereby executing the policies and charging rules made by the PCRF to these service data streams. When a bearer is established, the PCEF performs QoS authorization according to the rules sent by the PCRF, and performs gating control according to the enforcement of the AF. According to the charging rules sent by the PCRF, the PCEF executes a charging operation for a corresponding service data stream, and the charging can be online charging, and also can be offline charging. If it is the online charging, the PCEF needs to perform credit management together with an Online Charging System (OCS). When it is the offline charging, relevant charging information is exchanged between the PCEF and an Offline Charging System (OFCS). An interface between the PCEF and the PCRF is an interface Gx, an interface between the PCEF and the OCS is an interface Gy, and an interface between the PCEF and the OFCS is an interface Gz. The PCEF is generally located in the gateway of the network, such as a GPRS Gateway Support Node (GGSN) in a General Packet Radio Service (GPRS) and a Packet Data Gateway (PDG) in an Interworking Wireless Local Area Network (I-WLAN).
Similar to an architecture function of the PCC, a Broadband Forum (BBF) raises a Broadband Policy Control Function (Centralized Deployment Functional Architecture), and a major function of the BPCF is to make corresponding policies; Policy Enforcement Point (PEF) is generally resident in a fixed network transmission equipment such as a Broadband Remote Access Server (BRAS)/Broadband Network Gateway (BNG), and enforcement is performed according to the corresponding policies made by the BPCF; an Authentication, Authorization and Accounting (AAA) server stores user subscription information. The AF makes policies for the BPCF, and provides corresponding service information. Currently, an architecture of the BPCF is comparatively rough, and relevant details are still being further formulated.
At present, a Fixed Mobile Convergence (FMC) scenario to which many operators pay attention is mainly to study an interconnection between the 3GPP and the BBF. With regard to a scenario of the user accessing a mobile core network through a BBF fixed network, it is required to guarantee the QoS of the entire transmission path of data (the data will be transmitted through a fixed network and a mobile network). In the existing technology, an interface S9* (between the PCRF and the BPCF) is adopted for completion. In order to operate the services better, mobile operators expand wireless coverage, and considering from a cost-saving perspective, they will rent a line of WLAN access of fixed network operators. When the UE is connected to a wireless core network through a fixed network access system, the network will decide whether the fixed network access system is a trusted access network or an untrusted access network in an access authentication process. The actual deployment may have two situations.
1. The UE accesses a Residential Gateway (RG) through a Wireless Fidelity Access Point (WiFi AP), and accesses the Broadband Remote Access Server (BRAS)/Broadband Network Gateway (BNG) through an Access Note (AN) such as a Digital Subscriber Line Access Multiplexer (DSLAM), at the point, an Internet Protocol (IP) address of the UE is allocated by the RG, and an IP address of the RG is allocated by the BRAS/BNG. In order to save address space, the address allocated to the UE may be a private address, the RG is required to perform Network Address Translation (NAT) to the IP address of the UE in this case, and messages transmitted between the UE and HA need to be encapsulated through a User Datagram Protocol (UDP).
2. The UE performs access through the WiFi AP and accesses the BRAS/BNG through the AN, and the IP address of the UE is allocated by the BRAS/BNG at the point. Similarly, in order to save the address space, the IP address allocated by the BRAS/BNG to the UE or RG may also be a private IP address, the BRAS/BNG also performs NAT to the IP address of the UE at the point, and the messages transmitted between the UE and the HA need to be encapsulated through the UDP.
When the UE is connected to the wireless core network through a trusted access system of the fixed network operators, two interface modes of S2a and S2c can be adopted to perform connection. The interface S2a is based on a mobility management protocol Proxy Mobile IP Version 6 (PMIPv6), the UE must perform access authentication to the trusted access system; the interface S2c is based on a mobility management protocol Dual-Stack Mobile IP Version 6 (DSMIPv6), and when the UE is connected to the wireless core network through the access system of the fixed network operators at the interface S2c, the UE can directly perform authentication and authorization to the AAA server at the wireless core network side. In this case, the trusted access system of the fixed network operators can't know tunnel information of the UE, and thus the BPCF is unable to perform QoS guarantee to the data, passing through the fixed network access system, of the UE.